In order to meet the requirement of the International Telecommunications Union (ITU) on the future peak rate, the maximum bandwidth currently supported by the LTE-A is 100 MHz, while it is hard to find such a wide bandwidth in existing available spectrum resources. Additionally, a wide bandwidth complicates the hardware design of base stations and terminals. Moreover, a technology is urgently needed to make full use of the spectrum resources distributed in a plurality of frequency bands. Based on this consideration, a key technology of carrier aggregation is introduced in the LTE-A.
In carrier aggregation, the power imbalance among a plurality of component carriers adjacent in frequency causes severe image interference because image interference is caused once the image signal of a component carrier generated due to the In-phase/Quadrature (I/Q) gain imbalance and the integral error of the receiving circuit of a User Equipment (UE) falls onto another component carrier. Generally, if the power difference between the two component carriers is small and the UE passes a test on an image rejection requirement as specified in a standard, the image interference is small.
This small image interference causes no loss in system performance and is therefore ignorable. However, in some cases, the aggregation of component carriers required to cover different areas will lead to a great power difference between the component carriers. Then, the image of a large-power component carrier causes severe image interference to a small-power component carrier, which undermines the receiving performance of the small-power component carrier, degrades the overall communication performance of carrier integration and even interrupts communication. As such interference generally occurs in adjacent component carriers, such interference mainly occurs in an intra-band CA scenario and never occurs in an inter-band CA scenario.
The power imbalance refers to the power inequality between individual Resource Elements (RE), although the power difference between adjacent component carriers is not big in most scenarios and the power imbalance does not cause any significant problems, CA technology, with a capability of making good use of spectrum resources and increasing transmission rate, is attracting more and more operators, especially, with the application of more and more CA scenarios, the problem of the power imbalance between adjacent component carriers becomes more and more serious, and therefore, it is necessary to provide a method to address the problem of the power imbalance between adjacent component carriers.